I know this is kinda old, but i have some info id like to share to those who are searching the forum or google for info. I had a 84 tooth locking flex head that i loved. sadly i broke it, it was a case of extreme abuse, that would have broken any 1/4 tool BTW I broke it not using it as a ratchet. I warrantied it out. It took forever due to corona, but when i got my new tool it was a 90 tooth. I will tell you it has less slop in it, has the same size head. I took them apart and they have the same size gears and paws in them even though the cut out is smaller for the drive gear. Maybe thats why it has less paly in it. I also dont see why you couldnt rebuild it with a 84 tooth kit or a matco kit if thats what you have on hand. Its also lubed with a very thin oil which is what i have alway re-lubed my gearwrenches with. I have a few sets of gearwrench ratchets and when i brake a ratchet i grab one that i dont use as much or need at the time and I rebuild the one i need due to length or flex needed ext, so i can use it for the duration of my project then get a rebuild kit. I dont break ratchets very often but I like that option if it does happen.
By the way I didnt even have to mail the broken tool in, they just sent me a new one. As far as quality goes I have a locking flex armstrong 88 tooth and these gearwrenches are about 95 percent the quality. I do have a few protos that i got used and i like those just a hair more. I have a better selection of gearwrenches so they get get used more and i have no complaints. These gearwrenches are far above their price point weather 84 or 90 tooth